Collapsible corrugated plastic box

ABSTRACT

This invention provides a collapsible box made of corrugated plastic, which has improved hinge line/score line configurations between walls and panels and improved hand holds. A plastic box of this invention preferably has an automatically lockable bottom to facilitate erection of the box, and can be easily collapsed for return shipment and reuse.

This application is a Divisional of Ser. No. 09/,211,571, filed Dec. 15,1998.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to collapsible boxes and more particularly acollapsible box made of corrugated plastic.

2. Description of the Prior Art

Collapsible corrugated boxes and cartons made of paperboard are wellknown in the art. Such boxes and cartons typically include vertical sidewalls and top and bottom flaps on the side walls for forming a bottomend wall and a top closure for the box. The paperboard is crushed alonglines between adjacent side walls and between the side walls and theflaps to form “score lines” or hinge lines for bending the paperboard.

It is known to provide a foldable carton having hinged together bottompanels for automatically forming the carton bottom when the carton iserected. Cartons having such automatically forming bottoms are disclosedin U.S. Pat. Nos. 2,327,709 and 4,289,268.

It is also known to provide a plastic box as is disclosed in UnitedStates Pat. No. 4,948,039. That patent discloses a container made out offluted plastic having integral hinges between the walls and flaps andhaving Velcro® strips for fastening the walls and panels together. Thehinges in the container are made by cutting one facing sheet in thefluted plastic and hinging the walls and flaps on the other (uncut)facing sheet. The container disclosed in that patent is said to beeasily collapsible and reusable.

There is a need for an improved collapsible box made of corrugatedplastic that is economical and suitable for high speed manufacture anderection. An improved plastic carton is needed that is more durable andresistant to tearing. A plastic box is needed that will set up betterwhen erected and not collapse on itself. A corrugated plastic carton isneeded that includes an automatically lockable bottom and a plastic boxthat can be reused many times.

SUMMARY OF THE INVENTION

This invention satisfies the needs for an economical plastic box thatcan be manufactured using high speed equipment and which is durable andcapable of being reused many times.

This invention provides a collapsible box made of corrugated plastic,which has improved hinge/score line configurations between walls andpanels and improved hand holds. A plastic box of this inventionpreferably has an automatically lockable bottom to facilitate erectionof the box, and can be easily collapsed for return shipment and reuse.

A collapsible box of this invention may have offset scoring for thebottom flaps so the box sets up better. Offset scoring produces a boxwith less memory when erected, so the box stays erected withoutcollapsing on itself.

The score lines in a box of this invention preferably terminate short ofslots cut between panels and flaps so the corrugated plastic will haveincreased resistance to tearing. The box also preferably has hand holdsdefined by cut lines that terminate in rounded corners, which alsoreduce risk of tearing the plastic.

Accordingly, an object of this invention is to provide an improvedcollapsible box made of corrugated plastic.

The above and other objects and advantages of this invention will bemore fully understood and appreciated by reference to the followingdescription and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a collapsible box of the type suitablefor use with this invention.

FIG. 2 is a fragmentary cross-section through corrugated plastic for usein a box of this invention.

FIG. 3 is a plan view of a pattern or blank for a box having acollapsible lockable bottom suitable for use in this invention.

FIG. 4 is a bottom view of an erected box showing the locked bottomflaps.

FIG. 5 is a fragmentary view showing an offset score in a collapsiblebox of this invention.

FIG. 6 is a fragmentary cross-section through a hinge score of thisinvention before the corrugated plastic is folded at the score.

FIG. 7 is a fragmentary cross-section through a hinge score of thisinvention showing the corrugated plastic folded at the score.

FIG. 8 is a fragmentary view showing a diagonal score in a collapsiblebox of this invention.

FIG. 9 is a fragmentary view of a top corner of a box of this inventionshowing the score lines at the corner intersection of the side walls andtop flaps.

FIG. 10 is a fragmentary side elevation of a vertical width wall of abox of this invention showing a hand hold in the width wall.

FIG. 11 is a fragmentary cross-section through an alternative corrugatedplastic that can be used in the practice of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a collapsible box 10 that is suitable for use of thepresent invention. The box 10 is preferably rectangular or square infootprint but may also have hexagonal or other configurations. The boxhas a pair of vertical width walls 12, a pair of vertical length walls14, and a bottom closure 20 as is described below. The box optionallyincludes a pair of top width wall flaps 16 and a pair of top length wallflaps 18; it can also be in the form of a half slotted container, whichdoes not include top flaps.

The box 10 has vertical hinge lines 22 between the width walls 12 andlength walls 14, hinge lines 24 between the width walls 12 and widthwall flap 16, and hinge lines 26 between the length walls 14 and lengthwall flaps 18. The box also has hinge lines between the width walls 12,length walls 14 and bottom end wall flaps as is described below.

All score lines in the box 10 facilitate erecting and collapsing thebox. In accordance with this invention, a box 10 may have unique hingeline/score line configurations which improve the performance anddurability of the box.

Box 10 may also include hand holds 28 in opposite width walls 12. Thehand holds 28 are defined by a cut line 30 completely through the boxmaterial and may have a hinge/score line 32 at the top of each hand holdas is described below in more detail.

The top width flaps 16 may have hinge/score lines 34 across them forforming a bend at the line, and the top length wall flaps may haveL-shaped flaps 36 in them for providing slots to receive corners of thewidth flaps when the box 10 is closed by downward folding of the flaps16, 18. Each L-shaped flap 36 may be defined by a cut line 38 and ahinge/score line 40 so the flap can be hinged into the box to permitinsertion of the corners of flaps 16. The second flaps 36 provide a skiso the flaps can be inserted into the box without damaging the contentsof the box.

A box 10 of this invention may be made of corrugated sheet plasticmaterial 41 such as that shown in FIG. 2. Corrugated plastic 41 is wellknown material, but has received only limited application in collapsibleboxes (see U.S. Pat. No. 4,948,039). Corrugated plastic 41 has parallelfacing sheets 42, 44 and spaced, integral interconnecting ribs 46between the facing sheets. The plastic sheet material 41 can be easilyextruded from a variety of plastic resins such as polyethylene,polypropylene, and the like. A box of this invention may also be made ofconical plastic sheet material 80 such as that shown in FIG. 11, whichincludes facing sheets 81, 82 bonded to a corrugated intermediate sheet83 as for example by melt bonding, ultrasonic bonding or an adhesive.

FIG. 3 shows a blank 48 for a preferred embodiment of a box 10 of thisinvention. The blank includes panels which form the width walls 12,length walls 14, top width flaps 16, top length flaps 18, bottom widthflaps 50, bottom length flaps 52, 54 and glue flap 56. Score/hinge linesare also provided in the blank 48. These score lines may include scoreline 22 between the width walls 12 and length walls 16, score lines 24between the width walls 12 and length wall flaps 16, score lines 26between the length walls 14 and length wall flaps 16, scores 58 betweenthe width walls 12 and bottom end wall flaps 50, score lines 60 betweenthe length walls 14 and the length wall flaps 52, 54, score lines 60 inthe top width wall flaps 16, and score lines 62 in the bottom end wallflaps 50. The blank 48 also preferably has hand holds 28 in the widthwalls 12. The score lines 62 in each of the bottom width wall flaps 50bisect the corner where the width wall flaps meet the bottom length wallflap 52, 54, length wall 14 and width wall 12, and defines a tab portion64, which is to be adhesively bonded to the adjacent length flap to formthe automatically lockable bottom closure for a box made from the blank48.

Manufacture of a box 10 from the blank 48 is effected by shaping theblank into its box shape and gluing or otherwise connecting glue flap 56to the exterior surface of length wall 14. The bottom flaps 50, 52, 54are folded into a bottom closure, with flap 54 being folded first,followed by flap 52 and then flaps 50. Adhesive or glue has preferablybeen applied to the interface between tabs 64 and flaps 52, 54 toadhesively bond the tabs to the flaps at 66 as shown in FIG. 4.Alternatively, the tabs 64 can be joined or connected to flaps 52, 54 byultrasonic welding or a hook and loop closure.

In accordance with this invention, the hinge lines between the sidewalls 12, 14 and the bottom end flaps 50, 52, 54 of a box are preferablyvertically offset as is shown in FIG. 5. Such hinge lines preferably areformed by a crushed score line 68 and a perforated score line 70parallel to the crushed score line. The two score lines 68, 70 may bespaced apart approximately one to two times the thickness of thecorrugated plastic sheet material. The crushed score line 68 is formedby well known techniques in which a score tool or indenter is pressedagainst one face 42 of the corrugated material to collapse or crush theconnecting ribs 46 in the material (FIG. 6). The perforated score 72 isa line of perforations cut through one facing sheet of the corrugatedplastic. The crushed score 68 is preferably on the inside face (towardinside of box) of the plastic, and the perforations in the perforatedscore are preferably through the exterior face of the plastic, and theperforated score 70 is preferably the upper score in the hinge line.However, such locations of the scores are not critical to the invention.

FIG. 6 shows the parallel scores 68, 70 which form a hinge line of thisinvention, before the plastic 41 is folded or hinged, and FIG. 7 showsthe plastic after it has been folded. The weaker perforated score 70 isdesigned to fold first and provide the desired dimensional control inthe manufacture of the box. The crushed score 68 provides another bendpoint for the flap so each score has to accommodate only 90° of folding.This double hinged score enables the flaps to fold more easily andaccurately as compared to a single score.

The vertically offset, horizontal scores 68, 70 at the bottom ofadjacent walls 12 and 14 as seen in FIGS. 5, 6 and 7 provide morestability to a box of this invention. A box having such an offset scoresets up better and has less memory when erected. The reduction in memoryenables the box to stay erected without collapsing on itself. The bottomfull overlap flap 54 (FIG. 3) also tends to lay more flat in boxes withoffset scores, which is beneficial when filling the box with lightweight products like potato chips.

FIG. 8 shows diagonal hinge/score lines that may be used as analternative to the offset scores of FIG. 5. In the embodiment of FIG. 8,the score lines 72, 74 are parallel to each other, but extend diagonallyor at an angle (about 5-10°) to the score line 22 between the walls 12,14. This alternative is more typically used when the bottom or topclosure on the box has panels adapted to be closed and interlocked by aconventional French fold, instead of an automatically locking bottomclosure as illustrated in FIGS. 1 and 3. The purpose of the horizontallyrunning diagonal scoring is to alleviate the stress and memory involvedwhen all the scoring is on the same plane when mechanically interlockingthe top or bottom flaps, commonly known as French Folding the box. Ifthe scores run on the same plane, the flaps do not lay flat wheninterlocked; they bow outwardly a great deal. This is partially causedby the material being on the same plane and trying to occupy the samespace, when in reality, one flap need to be a little lower(approximately the thickness of the material being folded) than theadjacent interlocking flap. In order for the flaps to lock together, oneach flap, half is above the adjacent panel on one side, and tuckedunderneath the adjacent panel on the opposite side. Therefore, the scoreneeds to not run parallel to the floor, but diagonally to accommodatethe flap being higher on one end than the other. The diagonal scoringallows the flaps to lay flatter when engaged and helps minimize thepossibility of a load tipping due to the flaps bowing too much usingconventional scoring.

FIG. 9 shows additional features of the bend/score lines in a box ofthis invention. As seen in this figure, the score lines 22, 24, 26, 34between the walls 12, 14 and flaps 16, 18 terminate short of the edgesof the flaps and short of the slots cut between panels. For example,hinge/score line 34 in flap 16 and hinge/score lines 24, 26 betweenwalls 12, 14 and panels 16, 18 terminate approximately ½-1½ inches andpreferably 1 inch (1″) short of the edges of the flaps 16, 18.Terminating the scores short of the flaps helps reduce weak points thatcould start a tear. Tears tend to propagate in plastic once a tear hasstarted. Accordingly, prior art boxes having scores that extend into theslots between flaps are much more susceptible to tearing than are boxesof this invention.

The vertical hinge/score lines 22 also terminate short of the slot 17between flaps 16 and 18. A gap of unscored plastic approximately ½ inchlong is left at the end of each vertical score. This helps reduce weakpoints that could be the start of a tear in the plastic.

FIG. 10 shows a hand hold in a vertical width panel 12. The hand hold isformed by a cut line 30 across the bottom and up both sides of the handhold to define a flap 29 of plastic in the hand hold. It furtherincludes a score line 32 across the top of the hand hold 28 whichfacilitates hinging of the flap 29 of plastic. The score line 32 can beeither a crushed score or a perforated score and may be in either theinside or outside facing sheet in the plastic. However, the score line32 is preferably a crushed score on the inside face of the plastic. Inaccordance with this invention, the cut line 30 ends in a radius orrounded corner 76 at the top of the hand hold 28 on both sides of thehand hold. The rounded corners 76 move the stress point in the plasticaway from the top end of the vertical sides of the hand hold 28 andspreads the stress point to reduce risk of tearing the plastic duringlifting of a box of this invention. Conventional hand holds, which donot include rounded corners and which end parallel to the flute lines,tend to tear easily. The rounded corners 76 of the preferred embodimentshown in FIG. 10 spread the load across the score line 32.

It is therefore seen that this invention provides an improvedcollapsible box made of corrugated plastic that can be manufactured andassembled economically by high speed equipment. The box is moreconvenient to use and also more durable than prior art boxes. It will beapparent to those skilled in the art that numerous modifications can bemade to the preferred embodiments selected for illustration withoutdeparting from the invention or the scope of the claims appended hereto.For example, hook and loop fasteners, such as those made under the tradedesignation Velcro® by the Velcro Company, could be used to effectclosure of the top and/or bottom of the box.

What is claimed is:
 1. A collapsible box made of corrugated plasticcomprising: two vertical width walls; two vertical length walls; abottom width flap attached to each of said width walls through a hingeline; a bottom end flap attached to each of said length walls through ahinge line; one of said bottom end flaps hingedly connected to one ofsaid width flaps along a diagonal hinge line and the other said bottomend flap hingedly connected to the other said width flap along adiagonal hinge line to form an automatic lock bottom to said box; andsaid hinge lines between each of said width walls and their respectivewidth flaps and between each of said end walls and their respective endflaps comprising a crushed score line and a perforated score line whichis substantially parallel to said crushed score line.
 2. A collapsiblebox as set forth in claim 1 which includes a hand hold in each of saidvertical width walls and each hand hold comprises a cut line throughsaid corrugated plastic defining a hinged flap depending from a hingeline.
 3. A collapsible box as set forth in claim 2 in which said cutline terminates in a rounded corner on both ends of said hinge line fromwhich said flap depends.
 4. A collapsible box as set forth in claim 1which includes vertical hinge lines between each width wall and eachlength wall and said vertical hinge lines terminate short of the top andbottom of said walls.
 5. A collapsible box as set forth in claim 1 inwhich said hinge lines between said width walls and their respectivewidth flaps and said length walls and their respective width flaps allterminate short of the sides of said walls on both ends of each saidhinge line.
 6. A collapsible box as set forth in claim 5 in which saidhinge lines all terminate approximately one inch short of the sides ofsaid walls on both ends of each said hinge line.